Automatic distribution of content to mobile terminals, which may also be referred to as “podcasting”, is becoming increasingly important. In this respect, a “feed” is referred to as a document, typically an XML-document (XML: Extensible Markup Language) that contains references to network resources providing the contents to be distributed. These references within a feed are frequently updated. Typically, a feed contains a URI (URI: Uniform Resource Identifier) for each content. Typical formats of feeds are RSS1, RSS2, and ATOM. Details on these formats can be found in the RSS specification and in the atom syndication format specification RFC4287.
The general principle of feed-based automatic distribution of content is as follows: If a content provider wants to publish data, e.g. multimedia content such as audio data or video data, the content is made available through a URI. Typically, this URI is an HTTP address (HTTP: Hypertext Transfer Protocol), but can also link to any other kind of transport mechanism, e.g. BitTorrent. The URI of the newly published content is then added to the feed as an item. An item can contain information related to the content, such as title, summary or other information. In the RSS format, the URI of the content is appended to the item as an enclosure tag.
In order for a user to receive the automatically distributed content, a user's terminal is provided with a client for receiving the automatically distributed content on the basis of the feed. For example, such clients are referred to as “RSS readers”, “RSS clients” or aggregators. The client periodically retrieves the feed from a network resource which is referred to as a feed server. Typically, the feed is identified by an URI. If the user subscribes to a feed, the URI of the feed is added to the client. The client then periodically retrieves the feed from the feed server and, if the feed contains new items, proceeds to download the linked content. After downloading, the client informs the user that new content has been received.
The above concept of feed-based automatic distribution of content can also be applied to mobile terminals which communicate with the feed server and the content server via a mobile network, such as a GSM mobile network (GSM: Global System for Mobile Communications), a UMTS mobile network (UMTS: Universal Mobile Telecommunications Systems) or the like. However, in this case there exist problems in that the clients on the mobile terminals frequently retrieve the feeds and, for this purpose, establish connections to the feed and content service. For a large number of mobile terminals this results in increased bandwidth consumption.
Firstly, the feeds itself can become considerably large. There is no limit on the amount of items a feed can contain. If the feed provider doesn't prevent, a feed can grow endlessly. In this respect, it is known to restrict feeds so as to contain only a reduced number of recently published items, to contain a brief summary, or both. This in turn reduces the ability of referencing old content.
Secondly, bandwidth usage patterns in the mobile network change due to the feed-based automatic distribution of content. In particular, the clients use bandwidth in a different manner than a human user. A human user typically regularly checks for new content published by a favourite provider. This can be from a few times a month or week to several times a day. In feed-based automatic distribution of content, feeds and content are retrieved much more periodically (once or twice an hour) and from all content providers the user is subscribed to.
Thirdly, the mobile terminals each individually retrieve the feeds and contents from the respective servers, which means that the feeds and contents have to be transmitted in a point-to-point fashion which requires a large bandwidth.
Accordingly, there exists a need to provide improved techniques for feed-based automatic distribution of contents to mobile terminals coupled to a mobile network.